Year Number 1996 0.365160435438156 1998 0.426935762166977 2000 0.240109741687775 2002 0.410831212997437 2003 0.257701814174652 2004 0.452396661043167 2005 0.173916295170784 2006 0.414196908473969 2007 0.230479195713997 2008 0.209998890757561 2009 -0.07557762414217 2010 -0.182899221777916 2011 -0.708379745483398 2012 -2.03432869911194 2013 -1.72216212749481 2014 -1.71398878097534 2015 -1.6827712059021 2016 -1.61284875869751 2017 -1.90349066257477 2018 -2.08446145057678 2019 -2.21420574188232 2020 -2.14628767967224 2021 -2.33280539512634 2022 -2.47940897941589